Firearm



4 Sheets-Sheet l H. R. CLARKE June 4,' 1946.

FIREARM Filed Feb. 2, 1944 .Fugue 4, 1946. H. R. CLARKE I FIREARM 4 sheetsheet 2 Filed Feb. 2' 1944 Patented June 4, 1946 y FIREARM Howard R. Clarke, Newton-Highlands, Mass.-

Application February 2, 1944, SerialNo; 520,735:

(Cl. l2-3);

11Y Claims.

My present invention relates to automatic or semi-automaticV firearms of the type in which a piston-like action of the primer of a fired cartridge is utilized to unlock the bolt.

Various attempts have been made to utilize the forces developed byv and exerted on a red car'- trid'ge to unlock a bolt to provide the` basis of automatic or semiautoma'ti'c operation', These have been complicatedI and heavy i'n construction and unsatisfactory and unreliable in operation- In accorda-ncewitha preferred embodiment of my present invention, I" provide a firearm', the receiver of which slidably supports ar bolt' to reciprocate out of and intoa closed` position to extract and eject a' fired'cartri'olge;` re'cocl ;v the firing mechanism and to seat another cartridge in the chamber of the` barrel. The bolt comprises a shell having an axial passage and carries a cartridge engaging extractor. Rearwardly of its cartridge contacting front face, the bolt' shell has a plurality of lugs spaced to pass between lugs on the receiver as the bolt moves into or out. of its cartridge seating position and to engage therewith when the bolt shell is seated and partially rotated to lock" the bolt'to the receiver.

An actuator s'lidably' supported in the receiver'. has a cam connection with the bolt shell' effective toY rotate thev bolt shell intov its unlocked position when theactuator moves rearwardly relative thereto'and to rotate' the bolt shellinto itsl'ocked position when theactuatormoves forwardly relative thereto. The actuator is controlled, by resilient means to oppose its unlocking movement and the opening of the'bolt' and to urge the bolt towards its seated position and' to cause locking; movement of the actuator when the bolt shell isr seated.

The front part of the. axial passage ofthe bolt shell slidably supports a tappet which is in contact with the' actuator and has a pin or the like extending through a slot'in the shell of suicient lengthv to permit limited relative movement between the bolt shell and the tappet to permit the tappet to be driven rearwardly from a position in which it is actuated' bythe primer to drive the actuator through a working stroke adequate at least to cause unlocking of the bolt. The receiver is formed with a groove to receive the pin to hold the bolt shell against rotation except when seated.

It; will be helpful, in' understanding myinvention, to consider certain factors: at this time re.- lating to the. ring of. a cartridge and theV eiect ofgaspressure thereon.. It will also be. helpful. tobearinmind that the firing of acartrid'gerinf volves first'. the; explosion` ofi the primer; which isfollowed bythe ignition of the cartridgel charge'.- When the prim'er'isrexplod'ed', its explosionmay be: attended by movement ofi itrrelative to the car-- tridge case. Firing' o'f the main charge by the' primerI results ingas pressure effective first' t'o drive the cartridge caserearwardly to take up head space andi thenI to drive the primer rearwardly relativee to the cartridgefcase In accordancewith my invention, it; is the. piston-like action of the primer under the influence ofthe gas pressure of a fired charge-thatl` use tol efect the unlocking ofi thebol't'.

I have stated' that? the l'llfgs on'- the bolt; shellA and on the receiver serve tolock the-bolt to the:

' receiver. In practice', head-v space is always prof vided to ensure the operationof the bolt yunder'all conditions; Headv space is conventionally" closelyf limited to provide a; certain?. limited space between the frontI face of a closed; bolt and therear face of aseated cartridge. Headspace, however, may alsobe represented', at least in part, byf a spacebetween the lugsf whenv the bolt is closed'.`

When a cartridge is-iired, theI gas'pressurel in the barrel'- acts on the cartridge casel to expandv it against the chamb'er'and to` drive it rearwardly and-wherespface exists' betlween the receiver and bolt lugs, the gas? pressureiszalso effective to drive thebolt, within the limitsof the head space,.until arrested@ bythe receiver lugst Due to variationsin'violence of: primersiof con-V ventionalcartridges', some of the primers. when', red, move rearwardly relative to the. cartridge.

case a; limited distance before the: main: charge isfired". While' primers' are: conventionally^ coun'- tersunk withvrespe'ct tothe rear.' face ofi the car.- tridgeg. the possibilityf of. their. movementY musty be considered i'rrflrearmsin accordance 4with my invention. When'themain chargeof a cartridge is red, the: resulting -gas pressure is` effective to drive the primer rearwardly relativeto the. cartridge case,v The gas pressure` in the barrel is substantial.,V but decreases as the bullet approaches the muzzle of the barrel. When the bullet. leaves the barrel, the pressure drops olil fsharply.' The pressure remaining momentarily in the barrel after the bulletile'aves'it, maybe'termed"` residual pressure.

The timing of the relation between the unlocking'of the-bolt and the gas pressurein the barrel 50.' is of prime importancein providing safap'ositive andreli'able operation of lirearms ijnl accordancev with my invention. To meet-.these requirements,

I use the positive action of the primerr, when driven relative to the cartridgecaselbyl the gas pressures ofi-a1 red'; charge. toi.y givev the tappet. a

3 definite uninterrupted stroke. This stroke is sufcient to cause the actuator to be effective, through the cam connection, to rotate the bolt into its unlocked position and start its movement towards its open position at a time, preferably,

when only residual pressure is 'available to ensure completion of the movement of the bolt into its open position.

I accomplish this result by forming the groove in the receiver that guides the pin carried by the tappet so that the front end of the tappet, when the bolt is seated and locked, is spaced substantially flush with the front face of the bolt when the bolt and receiver lugs are in engagement. By this arrangement, movement, within head space limits, of the cartridge case, the bolt, or. y

both when a cartridge is fired, can have no effect on the tappet since the front end of the tappet is positioned rearwardly of the front face of the bolt unless and until the bolt lugs are in engagement with the receiver lugs. Because of head space, and because the forward movement of the tappet is limited, any movement of the primer, when it is red, can have no effect on the tappet. Since my invention provides for a denite-uninterrupted tappet stroke, it is only necessary to provide a cam connection between the actuatorv and the bolt shell to eiect the unlocking of the bolt at the right time in relation to the gas pressure in the barrel.

My invention also provides novel ejector means to eject an extracted cartridge. ,As the bolt reaches its open position, the pin carried by the tappet engages a stop, preferably carried by the stop which limits rearward movement of the bolt, tol cause the tappet to be driven forwardly relative'to the bolt shell to protrude beyond its front face thereby to eject the extracted cartridge. As the tappet strikes the primer, it tends to reseat it thereby ensuring against the primer being ,dislodged and dropping into the mechanism. The forwardend of the tappetis preferably larger than the primer and therefore cannot strike the countersunk primer of an unred cartridge and, as the bolt shell is again seated, the tappet is held by the pin guiding groove so that the bolt., shell moves forward relative thereto. When the bolt shell is seated, the actuatorunder the bolt actuating action of the resilientmeans, rotatesthe bolt shell into its locked position and returns to its normal position in contactV withv tion of the mechanism that is easy to control tov ensure accurate and safe operation.

This introduction of the rearm used to illustratermy invention makes it apparent that a characteristic feature of my invention is that the tappet is positioned relative to the receiver and independently of the bolt shell regardless of the 'specific construction of the bolt and the re,-

ceiver. l I Y L In vthe accompanying drawings `Ilhave shown, asan embodiment of my invention, a rearm of the carbine type fromk which these and other of its novel features andvadvantages will be readily apparent.

In the drawings: I f

. Fig. 1 is a fragmentary parti-al section showing 4 a iirearm in accordance with my invention ready to fire.

Fig. 2 is a plan section through the barrel and receiver with the parts in the positions shown in Fig. 1.

F Fig. 3 is a cross section along the lines 3 3 of Fig. 4 is a similar view along the lines 4--4 of Fig. 1.

Fig. 5 is a view similar to Fig. 1, showing the position of the parts immediately after the gun isred and the bolt is unlocked.

Fig. 6 is a plan section through the receiver and the barrel showing the position of the parts when the bolt is substantially in its open position.

Fig. 7 is an exploded view of the bolt parts.

Fig. 8 shows in an enlarged fragmentary view the relation of the bolt parts to a seated cartridge ,before firing.

Fig. 9 is a similar view showing the position of the bolt parts to a seated cartridge after ring but before the gas pressure has acted upon'the primer. v i

Fig. 10 is a similar View showing the position of the bolt parts when ejecting an extracted cartridge and Fig- 11 is a section alongthe lines II-II of Fig. 1. Fig, 12 is a View similar to Fig. 9 showing the position of the bolt parts as the tappet is driven rearwardly through its limited stroke by the primer to cause the actuator to effect the unlocking of the bolt shell, and Fig. `13 is a bottom View of the receiver showing the guide groove and the position of the pins in. section when the bolt parts are positioned as shown in Fig. 12 with their position in Fig. 9 being indicated by dotted lines. y

General construction At I0, I have showna receiverto which is` threaded a barrel II having a chamber I2. A stock I3 Vis suitably inlet for the receiver IU and the barrel l I and is clamped between the receiver I0 and the plate I4 by screws I5 and I6v which extend through the plate I4 and the stock I3 and are threaded into the receiver I0. The stock I3 is formed to house the trigger controlled firing mechanism, later to be described, which and the support l1 for the clip'I8 holding cartridges I9, are carried by the plate I4. The fore part of the stock I3 is also formed to house the spring powered bolt return means also later to be described, Which means also serve to oppose the unlocking of the bolt and its movement into its open position. Y

I have indicated generally at 20, a bolt slidably and rotatably Vsupported in the receiver II! to move, when the gun is red, from a closed and seated position (Figs. 1 and 2) in to and out of an open position (Fig. 6), to extract and eject a cartridge case through theslot 2 I, cock the firing mechanism, andY to pick up another cartridge from the clip I8 and to seat it in the chamber I2 ofthe barrel I I.

The bolt and receiver construction In accordancewith my invention, the bolt 20 consists of a bolt shell 22'which and the other bolt parts maybe seen most clearly in Fig. 7. The bolt shell 22 has ay countersunk cartridge engaging front facev 23 and is formed with an axial passage. 24 reduced as at 25 to establishA a seat andi a` front portion of slightly' greater-` diameter* than that of' the primersy 2li` of tlieA cartridges I9@ R'earwardly of' its cartridge; en'- gaging face 23; the boltshell 22.3 has? a plurality of llgs2 spaced tovpassL between lugs 28` on the receiver' as` the bolt shell moves intoand out' of its' seated: position` and to' aline therewith whenl theseated boltshell is partially-v rotated thereby to-establ'ish a locked bolt position. and 6.) The bolt shell 232 is'v formed to' receive an4 extractor Z9 which i's' detachably locked in place'byj a' friction' plug 3U'.

Withinthe bolt shell, Islidably mount a tappet 3l which is reduced in diameter ais` at 32 t'o' establish' a shoulder, engageable with the seat 25;

is unseatedV and' driven rearwardly relative' to itsl oase: by the gas pressure of the red charge.

The' tappet 3l' has' a transverse passage' 33 to slidably receive ai guide pin 34 which' extendsthrough' a slot' 35 in` the' bolt shell 22 and into a; guide' groove 35 inthe receiver til; The guide` groove 38 serves to' hold the bolt shell 22k againstv rotation when'Y it' is unlocked, that is, when it is positioned so that its lugs' 2'! may pass between the're'ceiver'lu'gs' 2`3and`, at its front end, extends laterally' as'at' 31', to permit rotation' of the bolt shell' 22' lwhen seated. The' slot 35` in the' bolt shell 22 limits relativemovement between' the bolt shell 22' and' the tappet' 3l' so that' the' tappet may have an eXtreme forward' position in' which its shoulder 32 is in' engagement with the seat "'and its front end protrudes' beyond the` front face 23' of the -b'olt shell (Fig. 10)' and a rear'- ward position in which it is set back by the. piston-like action of thefprim'erto' havev a working stroke against the actuator insuili'cient to permit the primer 2.6 to be entirely unseated (Fig. 5).

An actuator 38 is slidably housed within the' rear part of bolt shell passage' 24 and is of sucie'nt. length t'o protrude beyond thev rear face of the' bolt' shell' 22 when it is seated against the rear' face of the tappet 3|. The protruding rear end' of the' actuator 33 isY connected to' and slidably' guided by' the bolt return means.. I form the' actuator withA a transversely disposed passage 39 to receive a cam` pin 4t extending through a. cam slot 4l in the bolt shell 22. Preferably,

the end oiv the cam pin 40 also extends into the' guideY groove 35 in the receiver I0. On rearward p movement of the actuator 38 relative to the bolt shell 22, the cam connection is effective to rotate the bolt' shellV 22 into its unlocked position and, on forward movement of the actuator` 34 relative tothe bolt shell 22 under the influence of the bolt return` means, it is effective to rotate the bolt'. into' its` locked position. I form the cam slot 4I to establish a straight' front portion 42 and; a curved cam portion 43 (Fig. '7) so that initialrearward movement of the actuator is ineffective to rotate the bolt shell 22 thereby to provide a' delayin' unlocking the bolt shell 22 desired relation to thegas' pressure of a fired cartridge. On forward movement of the actuator 38, the guide groove 36 prevents the cam portion 43 from being effective to rotate the bolt shell 22until it is seated and then the actuator 38 moves relative to the bolt shell 22 to re-engage the'tappet 3 I.

The' tappet 3l' and the actuator 38, as shown in Figs. 6 and 7; are ea'c'h' formedwith axial pas'- (See Figs. 5

ano-nessi sages to slidably receive th'e'ring pin 44, with the. passage in thetappet1 3l, being. of smaller diameter than thatthroughthe actuator, 38. The front. portion gof. the firing -pin 44A isof. reduced diameter and.: the. thus established shoulder. `45 is. engageable with. the rear face of. the tappet 3+ to limitthe forwardstroke of. thering. pin. Intermediate the rea-r. portion ofthe firing pinl 44, itsr diameter is reduced as at 46. The guide pin` 34 and the cam pinA 40 haveV transverse passages41: and 4&respectively of the` sa-me vdiameter as the. reduced. portions. of. the; ring pin` Manci.v when. these register withA the axial. passages through the tappet and actuator, the bolt is coprectly assembled., 'I-he passageA 48 of the. cam pin. 4l)Y communicates with an` enlarged. passage. 49. of. suflciently large size toreceive the:v largest portion'. of` the-firing pin so that-thebolt may. be easilyv assembled. by;v placing the tappet 3l and.

-actuator 3%A within the bolt: shell. 22l with the passages-4l and 49 of the=guide pin' and cam( pinrespectively inalinement. with axial; passages throughY the tappetfand actuator.. The` firing pin, 44rna-y then. bev inserted untili-tsl reduoedportionl 45 is in registryl with` the. passage 49 of the. cam` pin 40. The cam pin 40: mayv thenbei shifted laterallyy of; the' bolt shell 22v soI that.. the: portion 46 entersthepassage 48. The;boltis-.then assem-- bled and the axiaL movement ot the lining pin. is limited., relativetothe actuaton to. establish a StIOke;

As shown in-.F-igs. 1.andi2; the-rear 4endofthe. receiver; may be2 threaded.. to receive a cap.v 50.V which is removable'to permitthef bolt 20' to-1 be removed when disconnected' from the bolt return nfieans.v In; practice; t-he. guidegroove'SG extends tothe rear endl of4 the receiver I0 sothat. the1 protruding pin; ends of the.- assembled bolt-l may be' entered therein.. The capYV 50 has a. boss. 5lx serving as ya stop-to limittherearward movement of the bolt 25 toldeneits open position and. is recessed to` accommodate:y the rear end.v of. the firing pin 44. Centeredby thezboss 5I` is aresili'- entstop 52- extendinginto the guide'grooveito be engagedby theu guidepin 34 asthebolt approaches the.f open. position. The' portion of. the stop 52 in the guide groove 3B isconvex in cross section and the endor the cam pin 40 is concave to straddle the stop 52 as shown inEig.. 3.

The bolt retummeans' The bolt' return; means (Figs: Il and 5) consists l 'pin` 581 Then receiver I`IJ` has transversely all'n'ed holes 55 by which the. pin 58 maybe' driven' out when in -ali'nem'ent therewith. A/ cover, not shown', serves' to'V prevent ingress4 of dirt. int'o'; the receiver' I 0" through the holes 591 One side of the' fore stockhas a' slot 60' (FigsjZ, 3, and' 4') ofsubstantiall'ythe length ofthestroke of the bolt 20 and this is closed' against the en trance of dirt to the. return means by one'v oft'he' arms 53' andt'o' this. I attach a charging handle 61 protruding outwardly formanual engagement;

, e Thefirina mechanism;

lWhere' semi-automatic voperation is desired,

firing 'mechanism inA accordance with my inven-` tionas may 'be seen in Fig: 1 consists of a ham- Y Vis formed with a pocketin which a release pawl 13 is pvotally mounted; The pawlv 13 extends through Va slot in the plate I4 to engage with the end portion |58a of the rod 65 so that when the trigger is pulled, the rod 65 is raised toV disengage from the surface 89 so that the spring 61 is operative to drive the'h-ammer 62 against Vthe rear end o'f the firing pin 44. I provide a spring 14 seated'between the plate |4 and the opposite end of the pawl 13 yieldably urging the pawl 13 into the position shown inv Fig. 1f. Y 1

By this construction, the pawl 13 yields, if the triggerV 1| is not re1eased,'when the rod 65 is forced rearwardly las the hammer is forced back by the'bolt 20 asit moves into its open position, and the sear connection becomes operative and cannot -be released until the trigger 1I is released thereby permitting the pawl 13 to again be positioned to raise theend of the rod B5.

, I attach the rear end ofthe trigger guardv 15 tothe plate I4 by'a screw 16 and at its front end, the trigger* guard is slotted as at 12 to receive the screw 11. At 19, I have shown the trigger guard 15 as formed with a'latch engageable with Y the catch 80 on the cartridge clip |8 by Ywhich theV clip is locked in place. Due to the resilience of the trigger guard 15'and to the fact that it is slidably connected to the plate I4 at its front end, the trigger guard may be squeezed to provide a convenient andeasil'y operated release to permit a. clip I8 to lbe removed and replaced.

- ,I l Operation The operation of a gun, in accordance with my invention, may be most readily appreciated by initial reference to Fig. 8 in which I have shown the bolt 20 in its seated and locked position with a cartridge I9 seated in the chamber vof the barrelII. M y

IDu'e to the fact that h'ead space isralways provided toV ensure proper bolt operation under all conditions, there-is space between the iront face of the bolt shell 22 and the rear face of a seated cartridge I9. Head space may, however, be pres.- ent,at least in part, between the receiver lugs 28 and bolt shell lugs 21and for that reason I have shown in Fig. 8 some spaceboth between the bolt shell lugs 28 andthe rear face of. the cartridge I9 andv between the boltrshell lugs 21 and receiver lugs 28.V Y

It will be understood that when a cartridge primer 2|i` is exploded, it may move rearwardly relative tothe cartridge case, but its action is uncertain as the violence of primers varies. After the primer 26'explodes, the main charge of the cartridge I9 is Vignited creating high gas pressure in the barrel I|.V The gas pressure acts agalnst'the cartridge casev to cause it to swell against-^ the chamber, to'stretch, and to vforce the cartridge .case rearwardly. This action takes upk head space and, unless the lugs-21,28 are in engagement, it forces the bolt shell 22 rearwardly until arrested by lug engagement. '1.

The gas pressure is then effective to drive the primer 26 rearwardly relative to the cartridge case and, as this movement of the primer is denite and positive, I use it to effect the unlocking4 of the boltv shell Y22 and the commencement of its movement towards its open position.

,'Io avoid the initial action of the primer, whenV it is exploded and the movement of the cartridge case, the bolt shellr or both, Within head space limits, from causing movement of the tappet 3|, I use the guide groove portion 31 to limit the forward position of the tappet 3| so that its forward L. end is substantially ilush with the fronty face 23 of the bolt shell 22 when the lugs are in engagement. By this arrangement, should the lugs not be in engagement, the front end of the tappet is set back with reference to the front face of the bolt shell so that it is not actuated by movement of the bolt within head space limits. At this point, it should be mentioned that if thetappet 3| were affected by the initial action of the primer or by movement of the cartridge case or bolt shell within head space limits, it would be Ygiven an interruptedstroke inadequate to cause reliable.

automatic or semi-automatic operation. l

The primers 26 of cartridges are conventionally countersunk and due to vthis and the space ensured between the tappet 3| and the primer 26 by positioning the tappet 3| with respect to the receiver I0, any initial action of the primer 26 does not contact the tappet 3 I.

Movement of the cartridge case, the bolt shell, or both, within head space limits, ensures that movement of the primer 26 under the iniluence of the gas pressure of a fired charge is effective to impart to the tappet 3| an uninterrupted stroke Yagainst the actuator 38. In Fig. 9, I have shownY the primer fired and all head space taken up so that movement of the primer 26 by the gas pressure of a red cartridge will impart such a stroke to the tappet 3|. In Fig. 12 I have shown the tappet 3| driven by the primer through the `limit of its stroke. The pin 34 is now` out of contact with thershoulder established by the front edge of the groove 31 and as the actuatorr38 continues its travel, it causes the bolt shell 22 .to rotate through its cam connection therewith, the Vpin 34 is positioned in alinement with the groove 36. In Fig. 13, I have shown the grooves 36 and 31. In Fig. V13, the pins V34 and 48 are rsectioned to indicate their position in Fig, l2.` Their'position shownV in Fig. 9 is indicated by dotted. lines and their general path is suggested by arrows,

The tappet stroke against the actuator 38, limited by the slot 35 in the bolt shell 22, drives the actuator rearwardly as shown in Fig. 5. Under'y this action, the actuator '38 moves rearwardlyY relative to the bolt shell 22 and then cams it into its unlocked position and is effective at least to start its movement towards its open position.

Because of the delayed opening of the boltshell.

rAs the bolt approaches its Vopen positiomjthe resilient stop 52 is engaged by the guide pin 34` so that further movement of the bolt shell 22 results in the tappet 3| occupying its extreme forit :strikes the primer f2.6 `of 'angextracted Vcartridge nndhinctionsasifan ejector. -(See;Fig. 1.0.-) Because the :front :end of the ltappet 4is -of 1greater .diameter than the primer, ;it cannot strike the -primer :.of fan unredacartridge. f

The :resilient -stop l'5.2 iis 4operative slightly in advance :ofthe .contact of the factuator t8 v'with Ethe boss 5,1, InFig. 6, Ithavefshown this ,relation fas exaggerated. MovementoftheboltZ towards Yits open position :is Ialso Vopposed by the 'bolt return .means Jandfby the ring mechanism which fitrecocks.

The vbolt 20 is 'returned Ifrom :its open `position by Vthe'return means to pick'upzanotherxcartridge I9 'from the clip I8 and :seat 'it in the :chamber IZJo the "barrel .l l. .Asthe '.b'oltshell 22 -is held 'againstrotation until it is seated, 4the faction :of the 'boltreturn means on the actuator 38 Iis .ineffective to rotate Athe bolt :shell 22. When r.the

bolt shell 22"is seated, the cam .connectionis'then operative to rotate itinto 'its Ylocked positionxand .then to permit the actuator `38 to Imoverelat'ive fto fthe `:bolt .shell `22 into contact with the tappet 3l. As the axial movement of the "firing-pin vlll is limited relative xto 'the actuator '38, it iis impossible'lfortheringpin 44 5to be in operative :relation tofa'cartridge until the bolt is inits locked :position *thereby ensuring safety in operation.

YConclusion nlthe Sforegoing, I have .described arearm in :accordance `with my invention which V,has .been successfully-operatedianditsfsuccess is dueto the snovel features :discussedin connection with it. "While'the description .has been .of :only Ynn'e ern-- lbodim'ent l'of my invention, ."lt will be apparent :from Tit that any :invention .provides zrearms :in- :expensive simple to manlfanture, saie tand `reliable in inse, ,and easy 'fto repair and cservice. :Contributing i-toithis :result .fareithe'many rfeatures that .il havesdiscussedan'd particularly :to the .fact -that ythe :tappet is :positioned positively relative tol the -`^receiver @and :independent of :the 'bolt zshell. v'lin addition, fattention ri'sldirected to the fact that the bolt rlshell .'22,the tappet 23|., Tand the actuator 3.8 fare light inrveight. This makes possible-fa :rapid acceleration and -rdeceleration ofthe parts that :may lbe'positively and I`accurately -controlled ftoprovidezsaf e, lemcienz .andreliable :.operation.

lWhait I therefore claimand desire to secure l'by LettersPatent is:

i1.. In a rearmtfor .use with "a cartridge :having fa centrally `disposed primer, :a receiver, 'a 'chambered'barrelcarriedby said receiver, "a bolt com- K'prisin'g -a bolt shell slidably Iand rotatably .cari rie'd'iby :said receiver 'to reciprocatel between fa cartridge seating position and aan lopen -1: o's'iti'on, `saidr bolt 5andchamber being proportioned to `'estaltilishhead space between Ysaid bolt and 'a seated cartridge 'when said bolt 'is 'in Asaid cartrid-geseatirgposition 'an actuator and ya l'-tappet Yslidabbly supported :axially of Esaid bolt shell for contac'twitl'i 'Leach other, means lto '-ho'ld Isaid V'ac- :actuator is driven by said .tappet and to urge ,fsaidfbolt shell into its closed and locked positions Lwhen .said -actuator is :driven by 'sa'id `:yieldable nneans, a pin `and slot connection between isaid tappetand'said bolt shell rlimiting relative move-- ment therebetween to provide an .'operativetaplpet strokeagainst said 'actuator and Ito "limit the `rnovernentiol the primer, and vsaid receiver fhav- 'ing a'groove 'to receive one end of thep-in of said Ypin and slot connection, said groove including a portion disposedin parallel with the axis of said barrel to hold said -bolt shelllagains't rotation' and a portion disposed at right angles theretofto permit limited partial rotation of 'said *bolt shell when seated, said last-named .portion being of sufcient width to ,permit limited `movement of fsaidt'appet therein and limiting the forward position .of vsaid tappet whensaidbolt is seated and flocked to .ensure `aV predetermined relation of the tappet to the primer of a seated 'cartridge regardless of whether head space is represented by .space .between said lugs, between said 'bolt and .said cartridge or vbothfthereby to ensure that .said 'tappet is given an` uninterrupted stroke by .thegas .pressure of afired cartridge acting only .through themoveinent of the primer.

v 2. .In a.rearm.for,use with .a cartridge having ya .centrally disposed primer, .a receiver, .a -chambered barrel .carried-bysaid receiver, a'bolt .corn- Kprising a :bolt shell .slidably and rrotatably .carried by .said 4receiver .to reciprocate between -acartridge seating `position .and ian ,open position, ,an .actu- .ator .and a tappet slidably vsupported .axially `of said bolt shell for .Contact Awith leach other and 4or .engagement .of .said .tappet .by .the primer-'and actuation :by `its piston-.like .action when ithe :cartridge is ined, .means `to 'hold said actuator :against .rotation,.said bolt shell .and said .receiver -each .including .lugs which, when said Ibolt shell .is seated and l,partially .-rotated, engage and .es- Atablish .a llocked .bolt position, ,yieldable means .urging said actuator against .said .tappet and opposing Ymovement ,of said actuator .by said Itap- `pet, 1a cam connection-between said actuator .and :said-.boltshellito urgesaid bolt shell linto .its .un-

locked and open positions when said actuator is driven by said Vtappet .and to yurge said boltshell into. its closed rand flocked positions when ysaid vactuatoris driven bysaid yieldable means, va pin wandlslotconnection between said -tappet-and said .bolt fshell limiting relative movement :therebetween to :provide Vlan .operative tappet stroke against said actuator and to limit the vmovement fof the primer, l'and said receiver having a guide groove :in parallel with'the taxis of lthe barrel to `:receive one 'end yof `the pin of fsaid pin and slot :connection to hold fsaid bolt Ashell against l.rotation :as -it reciprocates 'and .a pin 'accommodating groove disposed at right angles :thereto to `permit :partial rotation of said bolt shell when seated to establish a :shoulder 'in :said receiver locating the forward position of said tappet independentply of .said .bolt sh'ell'when #said rbolt is-seated and locked and to permitthe operative Astroke ,of said tappet.

3. The irearm of claim v12, in which 'a ffiring pin-fis supported axially of the tappet and actuator 'and Iis anchored to the actuator for limited vmovement `relative thereto, the 'cam .connection comprises a cam pin carried bythe actuator and the bolt shell hasa cam slot through which the cam pin extends, the front portion of the cam slot extends in parallel with Athe bolt axis, and the 'tappet and the actuator vare in "engagement `11 only when the cam pin is in the front portion of its slot so that as the bolt :moves under the iniiuence of the yieldable means the tappet and actuator are spacedfapart and the firing pin is inoperatively positioned exceptl when the bolt shell is seated and locked.

4. The firearm of claim 2, in which the cam connection comprises a cam pin carried Aby the actuator and the bolt shell has a pair of oppositely disposed cam slots through which the cam pin extends,A the pin and slot connection comprises a pin carried by the tappet and the bolt shell has a pair of oppositely disposed slots through which thev tappet pin extends, and one end of each ofthe pins is entrant of the guide slot in the receiver.

5. In a firearm for use withv a cartridge having a centrally disposed primer, a receiver, a chambered barrel carried by said receiver, a bolt comprising a bolt shell slidably and rotatably carried by said receiver to reciprocate between a cartridge seating position and an open position, an actuator and a tappet slidably supported axially of said bolt shell for contact with each other and for engagement of said tappet by the primer and actuation byits piston-like action when. the cartridge is fired', means` to hold said actuator against rotation, said bolt shell and said receiver each including lugs which, when said bolt shell is seated and partially rotated, engage and establish a locked bolt position, yieldable means urging said actuator against said tappet and opposing movement of said actuator by said tappet, a cam connection between said actuator and said bolt shell to urge said bolt shell into Vits unlocked and open positions Whensaid actuator is driven by said tappet and to urge said bolt shell `into its closed and locked positions when said vactuator is driven by said yieldable means, said bolt shell having a slot, and a pin carried by said tappet and extending through said slot to limit relative movement between said bolt [Shell Yand said tappet to provide an operative tappet stroke against said actuator to limit the movement of the primer, and to permit the front end of said tappet to have an ejecting position in which it protrudes a predetermined distance beyond the front face of said bolt shell, and said receiver having a guide groove in parallel with the axis of the barre1 to receive oneV end of the'tappet pin to hold said bolt shell against rotation as it reciprocates and a pin accommodating groove disposed at right angles thereto to permit partial rotation of said bolt shell when seated, to establish ashoulder in said receiver'locating the forward position of'said tappet independently YofY said Ibolt shell when said bolt is seated and locked, and to permit said tappet stroke, and stop means positioned in the rear end of saidV receiver and extending forwardly in said guide slot to engage with said pin to eiect its ejecting lposition as said bolt approaches itsopen posi- 6. The firearm of claim, in which-the stop means is resilient. v

7. The firearm of claim 5 in which the cam connection comprises a cam pin carried bythe actuator and the bolt shell has a cam slot through which the cam pin extends into the guide groove, and the groove entering end'of the cam vpin is formed to straddle the portion of the stop means that extends forwardly in the guide groove.

8. A bolt for a firearm comprising a firing pin, the rear part of which has a portion of reduced diameter, a bolt shell having a slot adlfcsll its assembly pin insertable through said cam shaped slot and through the transverse bore of said actuator, saidv assembly pins each having a transverse bore to receive said firing pin when alined with said passages, the transverse bore through vsaid second assembly pin being of keyhole shape, the larger part of which registers with the passage in said actuator before said second pin'is fully inserted to receive the rear end of said ring pinand the smaller part of which receives the portion of said firing pin which is of -reduced diameter when said second assembly pin is fully 'inserted thereby to lock said pin, said portionk of said firing pin'which is of reduced diameter being of greater length than the diameter of said second assembly pin. Y K

9. A bolt for a rearm comprising a ring pin, the front part of which is of lesser diameter than its'rear part to establish an intermediate shoulder and the rear part of which hasfa' portion of reduced diameter, a boltshell having a slot adjacent its front end and a cam shaped slot spaced rearwardly therefrom, an actuator anda tappet to be inserted into and slidably supportedby said bolt shell, said actuator and said tappet each hav-` ing an' axial passage for said firing pin respectively of the diameter of the-rear and front parts ofi-'said firing pin so that the rear face Yof'said tappet -constitutes a stop limiting the Vforward vposition of said yfiring pin, anda transverse bore intersecting said. passage, an assembly pininsertabl'e'throughrsaid first slot and through'the transverse bore `of said tappet, and a second assembly pin insertable through said cam` shaped slot and through the transversebore of said actuator, said assembly pins each having a' transverse bore to receiversaid firing `pin `when alined with said passages,'the transverse bore through said second assembly pin being of Akeyhole shape, the larger part of which registers with the passage'inv said 'actuator before said secondpin yis fully inserted to receive the rear'end of said ring pin and the smaller part of whichreceives the portion of said rring pin which is of reduced diameter when said second assembly pinis fully vinserted'thereby to lock said pin, said portion of said firingpin which is of reduced diameter ibevingof greater length than the diameter of'said second assembly pin'. Y A Y Y v 10.45. bolt for a firearmV comprising afiring pin, the front part of lwhich is of` lesser diameter, than its rear part to establish an intermediate shoulder and the rearpart of which has aportion of reduced diameter, `a bolt shell having a boreof reduced diameter in its forward portion and having a slot adjacent its front end and a cam shaped slot spaced rearwardly therefrom, an actuator and a tappet to be inserted into andslidably supported by said bolt shell, said actuator and said verse bore intersecting s aid passage, the front .portion of said tappet being of reduced diameter 1.70 61.11261 the portion of the boreof said bolt shell 13 which is of reduced diameter, an assembly pin insertable through said rst slot and through the transverse bore 'of said tappet, and a second assembly pin insertable through said cam shaped slot and through the transverse bore of said actuator, said assembly pins each having a transy verse bore to receive said firing pin when alined with said passages, the transverse bore through said second assembly pin being of keyhole shape, the larger part of which registers with the passage in said actuator before said second pin is fully inserted to receive the rear end of said firing pin and the smaller part of which receives the portion of said firing pin which is of reduced diameter when said second assembly pin is fully inserted thereby to lock said pin, said portion of said iiring pin which is of reduced diameter being of greater length than the diameter of said second assembly pin.

11. In a iirearm for use with a cartridge having a centrally disposed primer, a receiver, a chambered barrel carried by said receiver, a bolt carried by said receiver to reciprocate between a cartridge seating position and an open position, said bolt and said chamber being proportioned to establish head space between said bolt and a seated cartridge when said bolt is in said cartridge seating position, said bolt comprising a bolt shell having a cartridge contacting face, an actuator slidable with reference to said bolt shell, and a primer contacting tappet slidable with reference to said bolt shell and in engagement with said actuator when said bolt is in said cartridge seating position, means to lock said bolt shell against rearward movement when said bolt is in said cartridge seating position, means carried by said actuator to unlock said means, yieldable means urging said actuator forwardly and opposing its rearward movement, means connecting said actuator and said tappet to said bolt shell for movement relative thereto and to each other so that when said tappet is driven rearwardly by a primer, the rearward movement of said tappet relative to said bolt shell is limited, thereby limiting primer travel, and said actuator is driven rearwardly to eiect the unlocking of said lockin-g means and so that when said actuator is driven forwardly by said yieldable means, said bolt shell is carried into said cartridge seating position and in said cartridge seating position said actuator and said tappet are in engagement, and means carried by 

